This is the most important thing Anne-Marie Slaughter learnt from Hillary Clinton

Hillary Rodham Clinton (R) with Anne-Marie Slaughter (L)
KAREN BLEIER | AFP | Getty Images

Working with Hillary Clinton taught Anne-Marie Slaughter one life lesson she still carries with her today: Humor is important.

Talking to CNBC in an episode of "Life Hacks Live," Slaughter, now the chief executive of the New America Foundation, spoke about her time working with the former secretary of state.

And it was Clinton's humor more than anything else that she remembered.

"She's very funny, and people always say this about her privately, that she's very funny and witty and that she seems more stiff publicly," she says. At her meetings, which Slaughter says she attended every day, Clinton "was very good at just using a blend of wit and intelligence to move the meeting along."

"We were often facing really tough stuff but a little humor goes a long way," says Slaughter.

One occasion in particular stood out for Slaughter.

"There was one week where the deputy secretary of state just wasn't present. So the first day, that's fine," says Slaughter. "His chief of staff was there on the second day, and then on the third day, she's getting a little testy."

"The chief of staff says, 'Well, I'm here for Jim,' and she [Clinton] says, 'But where is he?' And the chief of staff says, 'Well, his wife's traveling this week and he's got the school run,' and she immediately says, 'Well, why didn't YOU just say so?'"

Slaughter says Clinton's joke "immediately broke the tension" while also demonstrating her high regard for family values.

Clinton's leadership style has meant she's developed a "very loyal" team, says Slaughter, simply because "she's a good person to work for."

"Life Hacks Live" is a series produced by CNBC International for Facebook, where tomorrow's leaders get to ask some of the world's biggest influencers for advice. You can watch the full episode here.

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